Directional drilling can be defined as the practice of controlling the direction and deviation of a wellbore to a predetermined underground target or location. Directional drilling has been an integral part of the oil and gas industry since the 1920s. While the technology has improved over the years, the concept of directional drilling remains the same: drilling wells at multiple angles, not just vertically, to better reach and produce oil and gas reserves. Additionally, directional drilling allows for multiple wells from the same vertical well bore, minimizing the wells’ environmental impact. Another advantage of directional drilling :
- Increasing the length of exposed section through the reservoir by drilling it at an angle
- Drilling into the reservoir when the vertical access is difficult. Oilfield under a town is an example
However, by drilling directionally, a country may steal another country’s oil, by placing the rig in its country region, but drill until another country’s region. This was happened in 1990, when Iraq accused Kuwait for stealing Iraq’s oil. Improvements in drilling sensors and global positioning technology have helped to make vast improvements in directional drilling technology. Today, the angle of a drill bit is controlled with intense accuracy through real-time technologies, providing the industry with multiple solutions to drilling challenges, increasing efficiency and decreasing costs.
Tools which are utilized in achieving directional drills including whipstocks, bottomhole assembly (BHA) configurations, three-dimensional measuring devices, mud motors and specialized drill bits. Now, from a single location, various wells can be drilled at numerous angles, tapping reserves miles away and more than a mile below the surface.
Many times, a non-vertical well is drilled by simply pointing the drill in the direction it needs to drill. A more complex way of directional drilling utilizes a bend near the bit, as well as a downhole steerable mud motor. In this case, the bend directs the bit in a different direction from the wellbore axis when the entire drillstring is not rotating, which is achieved by pumping drilling fluid through the mud motor. Once the angle is reached, the complete drillstring is rotated, including the bend, ensuring the drill bit does not drill in a different direction from the wellbore axis.
Directional drilling has brought enormous benefit to petroleum world. Oil fields once thought unreachable or dried up have found new life. Greater reserves are being accessed which were physically or economically inaccessible in the past. Another development is needed in order to gain advantage as much as possible.
Written by : Teguh Kristian Tampubolon